In a small bowl place the tomatoes, cover with boiling water and let tomatoes stand for 5 minutes then drain and chop them up coarsely.
While tomatoes are standing combine in a small bowl the soy sauce, vinegar, brown sugar, sesame oil, and red pepper flakes.
In a wok or large nonstick skillet, heat the vegetable oil over medium high heat until skillet is hot and then add the garlic and stir fry the vegetables for 30 seconds.
Take the cauliflower and broccoli, add it to the skillet and stir fry for 4 minutes and then add the tomatoes and bell pepper and stir fry the vegetables for 1 more minute or until the vegetables have become crisp tender.
Take soy sauce mixture and add it to the vegetables, then cook and stir the vegetables until they are heated through and serve immediately.